An olefin polymerization catalyst may be classified as a Ziegler-Natta heterogeneous catalyst or a metallocene single-site catalyst, and a metallocene according to the present invention has been developed for producing various polyolefin products since it was reported by Kaminski at 1980. The metallocene catalyst is composed of the combination of main catalyst having a transition metal compound as a principle ingredient with a co-catalyst having aluminum or boron as a principle ingredient. The polyolefin produced using the metallocene homogeneous single-site catalyst has a very narrow and homogeneous molecular weight distribution and chemical compositional distribution, and it is possible to freely control the tacticity, the comonomer response, the hydrogen response as the ligand structure of the metallocene catalyst, and to largely improve the related physical properties of the polyolefin compared to the use of a Ziegler-Natta catalyst.
In order to apply the metallocene catalyst to a slurry or vapor phase olefin polymerization process, an immobilization support is needed. The reason is that processing problems such as agglomeration, fouling, sheeting, plugging phenomenon or the like of the produced polymer in case of incorporating the homogeneous metallocene catalyst into the vapor phase polymerization process are encountered, thus the shape of the produced polyolefin polymer particle is very irregular and the apparent density is low so that the production of the product is impossible.
In order to solve these several problems, a study on the immobilization was conducted on the polymerization method of the polyolefin including supporting the metallocene alone or metallocene and co-catalyst using several porous inorganics or organics such as silica, alumina, magnesium dichloride and the like to prepare the metallocene supported catalyst, and applying them to the slurry or vapor phase polymerization process.
Conventional metallocene catalyst supporting methods include for example, supporting the metallocene after treating by adding an aluminum compound, that is, trimethylaluminum, triethylaluminum and the like to the unplasticized silica (U.S. Pat. Nos. 4,937,217, 4,912,075 and 4,935,397), preparing the metallocene supported catalyst by adding the metallocene after surface-treating the plasticized silica by methylaluminoxane or surface-treating the silica containing water by alkylaluminum (U.S. Pat. Nos. 4,808,561, 4,912,075 and 4,904,631), etc. In addition, synthesizing the metallocene supported catalyst by adding metallocene after surface-treating the silica by using the boron-based organometallic material instead of the aluminum organometallic compound (U.S. Pat. No. 6,087,293), and preparing the metallocene supported catalyst by surface-treating of the silica by using the organic compound instead of organometallic compound of aluminum or boron-based and contacting them with metallocene (U.S. Pat. Nos. 5,643,847 and 5,972,823) are known, and attaching the metallocene catalyst to the silica surface by forming the covalent-bonding through the chemical reaction (Korean Patent Application No. 10-1999-0023575 and Korean Patent No. 10-0536181) are known.
However, by preparing the supported metallocene catalyst by the above-mentioned methods, there are disadvantages in that the catalyst component is not homogeneously supported in the pore, the time required for preparing the catalyst is long, and the activity of the catalyst is low. In addition, problems such as deactivation and a hot spot in the reactor may be caused because aluminoxane is not homogeneously distributed in the pore. The polymerized polymer particle is able to cause the fouling or plugging phenomenon by dissolving out the catalyst component in the supported metallocene catalyst in the slurry polymerization process. The method for preparing the supported metallocene catalyst through the chemical bonding that was already developed to solve the above-mentioned catalyst elution problem has disadvantages in that the cost for preparing catalyst is high and the activity of the prepared catalyst is low due to the method requiring several stages.